Shares of the Las Cruces, New Mexico, company were falling 4.7% to $56.65 at last check.
"We have decided to allow more time for technical checks,” the company tweeted Friday. “We are working to identify the next flight opportunity."
Virgin Galactic had identified a flight window opening Saturday to run through the month so another test could be scheduled soon.
Virgin, founded and partly owned by British entrepreneur Richard Branson, said earlier this month that a new flight window for the vessel would start Saturday.
The company's planned flight on Dec. 12 was ditched when the onboard computer halted ignition of the rocket motor.
The FAA had announced that airspace around Virgin Galactic’s takeoff point at Spaceport America in New Mexico would be restricted for space operations from 9 a.m. ET Saturday until 6 p.m. on Sunday.
Investors took to Twitter to voice their displeasure with the announcement.
"Are you not flying this flight window at all?" one person wrote. "Very vague tweet . Not very professional for investors to leave us in the not knowing."
"Unprofessional and Irresponsible," another tweeted. "Your shareholders additionally purchased call options to indicate enthusiasm for the flight. What have you done?"
One commenter was more sympathetic, saying "guys all this means is that they are doing more preflight checks before they fly."
"They have a few days to fly so they could literally update later today and say Sunday instead," he wrote. "My gut tells me valentines day..."
On Tuesday, UBS analyst Myles Walton downgraded Virgin Galactic to neutral from buy with a price target of $52, up from $35.
Walton said that while he remains "convinced" in the fundamentals of the company's offerings, the rating change was driven by the "stratospheric" move in the stock price of more than 300% since the fall.